Contact cooling means



ApriI BO, 1963 J, P WATSON 3,083,013

CONTACT COOLING MEANS Original Filed April 2, 1956 FIG. 2

INVENTOR JAMES P. WATSON BYAJWTW ATTORNEY Uite States This invention relates primarily to contact cooling means, and more particularly to contact cooling means for use in a snap acting leaf-spring-type electric switch.

It is an object of this invention to provide a contact cooling means that will greatly increase the operating life of snap acting switches.

It is another object of this invention to provide means for prolonging the contact life of a switch mechanism, thereby making the mechanism capable of standing many millions of circuit openings and resultant arc formations.

In accordance with these and other objects which will become apparent hereinafter, preferred forms of the present invention will now be described in connection with the accompanying drawings wherein:

FIG. 1 is a fragmentary view illustrating one form of the present invention and showing the switching element flexed to its left hand position;

FIG. 2 is a fragmentary section taken on line 22 in FIG. 1;

FIG. 3 is a top plan view taken on line 3-3 in FIG. 1; and

FIG. 4 is a fragmentary enlarged elevation taken in the same direction as FIG. 1 and showing the switching element flexed to its right hand position.

One of the reasons for switch mortality is the fact that the are formed when the contacts separate causes burning of the contacts, so that they soon fail to make good electrical connection when they come into contact with each other. One means for prolonging contact life against this life-shortening arc action is shown in the embodiment of this invention illustrated in FIGS. 1, 2, 3 and 4.

In the embodiment shown in the drawings 62b designates a normally closed housing but is shown opened in the drawings to reveal the inner mechanism. Three terminals 127 and 161 extend from an end of the housing and the terminals 127 each supports a bracket 12 6 on which stationary contacts are mounted, as will be de scribed.

A flexible leaf spring 36b is pivotally journalled in the inner end of terminal 161. A flexible conductor 162 electrically connects the leaf spring 3612 to the terminal 161.

Any suitable means, not shown, may be provided to effect snap-over fiexure of the leaf spring 36b to cause the intermediate portion thereof to move laterally as seen in FIG. 1. This lateral movement causes the contacts carried by the leaf spring to snap between the stationary contacts carried by brackets 126, as will be described.

One form of means for cooling the contacts is shown in the form of a gas pumping means consisting of a compressible bellows 117, one wall 118 of which is substantially fixedly mounted with respect to the switch housing, and the other wall of which is mounted to the leaf 36b. Compressible and expandable between the two members 36b and 118 is the accordion-like bellows 117. At the upper end of the bellows 117 is a small pipe 119 which communicates with the interior of the bellows 117 and which leads air inhaled and exhaled by the bellows 117 around the side of the leaf 36b to a nozzle 121 which is directed across the face of the stationary contact 57b.

In the position shown in FIG. 1, the bellows 117 is filled with air. When the leaf 36b snaps to the right, air is forced from the bellows 117 and out the nozzle 121,

atent 3,088,013 Patented Apr. 30, 1963 ice over the contact surface of the stationary contact 57b. This blast of air not only cools the contact surface, but also removes from the contact zone the products of the electric arc, namely the gases and the tiny solid products of the electric arc formed upon breaking of the circuit.

A similar bellows 122 is mounted on the opposite side of the leaf 36b and likewise has a pipe 123 and nozzle 124 to direct a blast of air across the opposite stationary contact 58b.

It will be seen that, in operation, the bellows 117 and 122 alternatively inhale and exhale whatever gas the interior of the housing 6212 may be filled with, thereby directing a cooling stream of such gas across whichever pair of contacts is open circuiting.

The invention provides, therefore, an improved switching assembly in which contact life is prolonged by protecting the contacts of the switch against the life shortening action of the arcs which tend to occur when the switch contacts are opened. This, as fully described above, is achieved by the improved mechanism of the invention by means of which a blast of air is blown across the contact surface to remove the products of the electric are from the contact zone and to cool the contact surface.

This application is a division of copending application Serial No. 575,467; filed April 2, 1956; for Snap Acting Mechanism which has now issued as Patent 2,964,602.

While the instant invention has been shown and described herein in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope of the invention, which is therefore not to be limited to the details disclosed herein, but is to be afforded the full scope of the claims.

What is claimed is:

1. Switch mechanism comprising: a housing support means positioned within said housing, leaf spring means pivotally journalled at at least one of the ends thereof in said support means and having actuating means to effect snap-over fiexure and pivotal movement thereof about said one end, a first contact means mounted within said housing and having a contact surface, a second contact means mounted on said leaf spring means so as to be selectively movable toward and from said contact surface of said first contact means in a direction substantially normal thereto, by said snap-over action to close and open an electric circuit, a compressible bellows having one wall substantially fixedly mounted with respect to said housing and having a second wall mounted to said leaf spring means, said bellows being compressible and expandable as said leaf spring means moves between a first and a second position selectively to open and close said first and second contact means, and nozzle means stationarily mounted in said housing and coupled to said bellows and directed towards the space between said first and second contact means and across said contact surface for directing a stream of fluid thereacross as said first and second contact means open, said stream of fluid serving to cool the contact surfaces of said first and sec- 0nd contact means and to remove from the zone of the first and second contact means the products of the arc formed upon opening of the first and second contact means.

2. Switching mechanism according to claim 1 and which includes a third contact means mounted within said housing spaced from said first contact means, a fourth contact means mounted on said leaf spring on the opposite side thereof to said second contact means so as to be selectively engageable and disengageable with said third contact means to close and open an electric circuit, a second compressible bellows having one wall substana 3 tially fixedly mounted with respect to said housing and having a second wall mounted to said leaf spring means on the opposite side thereof to said second wall of said first named bellows, said second bellows being compressible and expandable as said leaf spring means moves 5 between said first and second positions selectively to open and close said third and fourth contact means, and further nozzle means stationarily mounted in said housing, coupled to said second bellows and directed between said third and fourth contact means for directing a stream of 10 fluid therebetween and across said third contact means as said third and fourth contact means open.

References (Iited in the file of this patent UNITED STATES PATENTS 515,374 Sperry Feb. 27, 1894 608,134 Lundell July 26, 1898 FOREIGN PATENTS 257,014 Great Britain Aug. 20, 1956 

1. SWITCH MECHANISM COMPRISING: A HOUSING SUPPORT MEANS POSITIONED WITHIN SAID HOUSING, LEAF SPRING MEANS PIVOTALLY JOURNALLED AT AT LEAST ONE OF THE ENDS THEREOF IN SAID SUPPORT MEANS AND HAVING ACTUATING MEANS TO EFFECT SNAP-OVER FLEXURE AND PIVOTAL MOVEMENT THEREOF ABOUT SAID ONE END, A FIRST CONTACT MEANS MOUNTED WITHIN SAID HOUSING AND HAVING A CONTACT SURFACE, A SECOND CONTACT MEANS MOUNTED ON SAID LEAF SPRING MEANS SO AS TO BE SELECTIVELY MOVABLE TOWARD AND FROM SAID CONTACT SURFACE OF SAID FIRST CONTACT MEANS IN A DIRECTION SUBSTANTIALLY NORMAL THERETO, BY SAID SNAP-OVER ACTION TO CLOSE AND OPEN AN ELECTRIC CIRCUIT, A COMPRESSIBLE BELLOWS HAVING ONE WALL SUBSTANTIALLY FIXEDLY MOUNTED WITH RESPECT TO SAID HOUSING AND HAVING A SECOND WALL MOUNTED TO SAID LEAF SPRING MEANS, SAID BELLOWS BEING COMPRESSIBLE AND EXPANDABLE AS SAID LEAF SPRING MEANS MOVES BETWEEN A FIRST AND A SECOND POSITION SELECTIVELY TO OPEN AND CLOSE SAID FIRST AND SECOND CONTACT MEANS, AND NOZZLE MEANS STATIONARILY MOUNTED IN SAID HOUSING AND COUPLED TO SAID BELLOWS AND DIRECTED TOWARDS THE SPACE BETWEEN SAID FIRST AND SECOND CONTACT MEANS AND ACROSS SAID CONTACT SURFACE FOR DIRECTING A STREAM OF FLUID THEREACROSS AS SAID FIRST AND SECOND CONTACT MEANS OPEN, SAID STREAM OF FLUID SERVING TO COOL THE CONTACT SURFACES OF SAID FIRST AND SECOND CONTACT MEANS AND TO REMOVE FROM THE ZONE OF THE FIRST AND SECOND CONTACT MEANS THE PRODUCTS OF THE ARC FORMED UPON OPENING OF THE FIRST AND SECOND CONTACT MEANS. 